H1N1 Influenza Information

2009

GENERAL INFORMATION
What is 2009 H1N1 (swine flu)?
2009 H1N1 (sometimes called “swine flu”) is a new influenza virus causing illness in people. This new virus was first detected in people in the United States in April 2009. This virus is spreading from person-to-person worldwide, probably in much the same way that regular seasonal influenza viruses spread.

Why is 2009 H1N1 virus sometimes called “swine flu”?
This virus was originally referred to as “swine flu” because laboratory testing showed that many of the genes in this new virus were very similar to influenza viruses that normally occur in pigs (swine) in North America. But further study has shown that this new virus is very different from what normally circulates in North American pigs. It has two genes from flu viruses that normally circulate in pigs in Europe and Asia and bird (avian) genes and human genes.

Are there human infections with 2009 H1N1 virus in the U.S.?
Yes. Human infections with 2009 H1N1 are ongoing in the United States. Most people who have become ill with this new virus have recovered without requiring medical treatment.

Is 2009 H1N1 virus contagious?
The 2009 H1N1 virus is contagious and is spreading from human to human.

How does 2009 H1N1 virus spread?
Spread of 2009 H1N1 virus is thought to occur in the same way that seasonal flu spreads. Flu viruses are spread mainly from person to person through coughing or sneezing by people with influenza. Sometimes people may become infected by touching something – such as a surface or object – with flu viruses on it and then touching their mouth or nose.

How long can an infected person spread this virus to others?
People infected with seasonal and 2009 H1N1 flu shed virus and may be able to infect others from 1 day before getting sick to 5 to 7 days after. This can be longer in some people, especially children and people with weakened immune systems and in people infected with the new H1N1 virus.

What states have reported influenza activity?
Thirty-seven states are reporting widespread influenza activity at this time. They are: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Minnesota, Mississippi, Missouri, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, South Carolina, South Dakota, Texas, Tennessee, Virginia, Washington, and Wyoming. Any reports of widespread influenza activity in September and October are very unusual.

SIGNS, SYMPTOMS, AND SEVERITY
What are the signs and symptoms of this virus in people?
The symptoms of 2009 H1N1 flu virus in people include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue. Some people may have vomiting and diarrhea. People may be infected with the flu, including 2009 H1N1 and have respiratory symptoms without a fever. Severe illnesses and deaths have occurred as a result of illness associated with this virus.

How severe is illness associated with 2009 H1N1 flu virus?
Illness with 2009 H1N1 virus has ranged from mild to severe. While most people who have been sick have recovered without needing medical treatment, hospitalizations and deaths from infection with this virus have occurred.
In seasonal flu, certain people are at “high risk” of serious complications. This includes people 65 years and older, children younger than five years old, pregnant women, and people of any age with certain chronic medical conditions. About 70 percent of people who have been hospitalized with this 2009 H1N1 virus have had one or more medical conditions previously recognized as placing people at “high risk” of serious seasonal flu-related complications. This includes pregnancy, diabetes, heart disease, asthma and kidney disease.
Young children are also at high risk of serious complications from 2009 H1N1, just as they are from seasonal flu. And while people 65 and older are the least likely to be infected with 2009 H1N1 flu, if they get sick, they are also at “high risk” of developing serious complications from their illness. See people at High Risk of Developing Flu-Related Complications below for more information about who is more likely to get flu complications that result in being hospitalized and occasionally result in death.
How does 2009 H1N1 flu compare to seasonal flu in terms of its severity and infection rates?
With seasonal flu, we know that seasons vary in terms of timing, duration and severity. Seasonal influenza can cause mild to severe illness, and at times can lead to death. Each year, in the United States, on average 36,000 people die from flu-related complications and more than 200,000 people are hospitalized from flu-related causes. Of those hospitalized, 20,000 are children younger than 5 years old. Over 90% of deaths and about 60 percent of hospitalization occur in people older than 65.
When the 2009 H1N1 outbreak was first detected in mid-April 2009, CDC began working with states to collect, compile and analyze information regarding the 2009 H1N1 flu outbreak, including the numbers of confirmed and probable cases and the ages of these people. The information analyzed by CDC supports the conclusion that 2009 H1N1 flu has caused greater disease burden in people younger than 25 years of age than older people. At this time, there are relatively fewer cases and deaths reported in people 65 years and older, which is unusual when compared with seasonal flu. However, pregnancy and other previously recognized high risk medical conditions from seasonal influenza appear to be associated with increased risk of complications from this 2009 H1N1. These underlying conditions include asthma, diabetes, suppressed immune systems, heart disease, kidney disease, neurocognitive and neuromuscular disorders and pregnancy.

HIGH RISK GROUPS AND SPECICAL CONSIDERATIONS FOR RETT SYNDROME
Is my daughter with Rett syndrome at higher risk for complications?
Individuals with disorders that can compromise respiratory function or the handling of respiratory secretions or that can increase the risk for aspiration (e.g., cognitive dysfunction, spinal cord injuries, seizure disorders, or other neuromuscular disorders) are considered to be at a higher risk for complications.

The Center for Disease Control and Prevention (CDC) in Atlanta reports that 477 people in the US have died from H1N1 influenza (flu), including 36 children, as of August 8th, 2009. Nearly 70 percent of these children had chronic high-risk medical conditions such as epilepsy, cerebral palsy or developmental delay, according to data published in the September 4, 2009 edition of MMWR News (http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5834a1.htm).
“These findings emphasize the importance of caretakers of children with chronic medical conditions consulting their physicians about obtaining vaccinations against H1N1 before the vaccine becomes available, currently estimated to be in October of 2009. Today, an estimated 300,000 children under the age of 14 have epilepsy in the United States,” said Robert S. Fisher, M.D., Ph.D., Editor-in-Chief of epilepsy.com, which is dedicated to furthering the mission of Epilepsy Therapy Project.
Others at increased risk for seasonal influenza-related complications:
•    Children younger than 2 years old;
•    Adults 65 years of age or older
•    Pregnant women
•    Persons with the following conditions:
o    Chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, hematological (including sickle cell disease), or metabolic disorders (including diabetes mellitus);
o    Immunosuppression, including that caused by medications or by HIV;
o    Persons younger than 19 years of age who are receiving long-term aspirin therapy, because of an increased risk for Reye syndrome.

What should I do if my child is at a higher risk?
Actions that would be recommended for high risk populations are avoidance of those with flu symptoms and crowds unless necessary. Frequent handwashing is important. Vaccinations against the virus are available. When the time comes, follow the CDC’s and your physician’s recommendations on who should receive the H1N1 and regular flu vaccinations. (See description of different H1N1 vaccinations below.)
Early treatment with antiviral medications (oseltamivir, trade name Tamiflu® or zanamivir, trade name Relenza®) is recommended for all people with suspected or confirmed influenza who require hospitalization. Stay home until your fever is gone for at least a day.

One of the common complications and apparent cause of death from the virus is pneumonia, so vaccination with the Pneumovax vaccine may be helpful. You should discuss this with your child’s primary physician.

ANTIVIRAL TREATMENTS:
What are antiviral medications, how are they used, who should use them, and what are the side effects?
Influenza antiviral drugs are prescription drugs (pills, liquid, or inhaler) that decrease the ability of flu viruses to reproduce. While getting a flu vaccine each year is the first and most important step in protecting against flu, antiviral drugs are a second line of defense in the prevention and treatment of flu.
For treatment, antiviral drugs should be started within 2 days after becoming sick. When used this way, these drugs can reduce the severity of flu symptoms and shorten the time you are sick by 1 or 2 days. They may also prevent serious flu complications.
Antiviral drugs may be especially important for people who are very sick (hospitalized) or people who are sick with the flu and who are at increased risk of serious flu complications, such as pregnant women, young children and those with chronic health conditions.
When used to prevent the flu, antiviral drugs are about 70% to 90% effective against susceptible viruses (i.e., viruses that are not resistant to the antiviral medication). It’s important to remember that flu antiviral drugs are not a substitute for getting a flu vaccine.
What side effects can occur with influenza antiviral drugs?
Side effects differ for each drug. If an antiviral drug has been prescribed for you, ask your doctor to explain how to use the drug and any possible side effects. Health care professionals prescribing flu antiviral drugs should alert patients about adverse events that can occur.
Can antiviral drugs be helpful for people unable to take the flu vaccine?
Yes. CDC and ACIP recommend use of antiviral drugs for people allergic to eggs (which can cause them to have an allergic reaction to the vaccine) or for people who previously have encountered complications from Guillain-Barre syndrome (GBS) associated with influenza vaccination. In addition, taking antiviral drugs may be recommended among persons that may not have a good immune response to the flu vaccine.
Should people use antiviral drugs before or after receiving the live attenuated influenza vaccine (LAIV) called FluMist®?
LAIV is one of two types of flu vaccine. It is given as a nasal spray and contains weakened, live virus. Flu antiviral drugs taken from 48 hours before through 2 weeks after getting LAIV can lower or prevent the vaccinated person from responding to the vaccine and the person may not get immune protection from the vaccine.
Antiviral drugs can be taken with the inactivated (i.e. killed) flu vaccine.
Can children take antiviral drugs?
Yes. The two drugs recommended for use against influenza (including 2009 H1N1) this season can be used in children.
•    Oseltamivir (Tamiflu®) is approved by the Food and Drug Administration (FDA) for use in children 1 year of age or older. In addition, in July 2009, the FDA issued an Emergency Use Authorization (EUA) for the use of Tamiflu ® in pediatric patients younger than 1 year of age.
•    Zanamivir (Relenza®), is approved for treatment in children 7 years and older, but is licensed only for use in people without underlying respiratory or heart disease, including people with asthma.

What kind of antiviral drugs are available for children?
Oseltamivir (Tamiflu®) comes in an oral suspension (liquid) for children. It also comes in capsules at children’s dosages. Zanamivir (Relenza®) is an inhaled powder that comes with a disk inhaler.
What are the recommendations for the use of antiviral drugs in young children?
Children younger than 2 years old should be considered for early empiric treatment with the antiviral drug oseltamivir if they have suspected or confirmed flu. Hospitalization data available found that children younger than 2 years old were at increased risk for flu-related complications compared to older populations. During April through August 2009, hospitalization rates for lab-confirmed 2009 H1N1 influenza in children younger than 2 years old was 2.5 times higher than the rates for children 2 years to 4 years old. In studies of seasonal influenza, the risk for hospitalization is also highest for infants, with the risk decreasing as a child gets older.
Given this increased risk for hospitalizations, children younger than 2 years are generally recommended for antiviral treatment. Children ages 2 years to 4 years old without high risk conditions and who are not severely ill do not necessarily need antiviral treatment. While children 2 years to 4 years old are more likely to require hospitalizations or urgent medical care for influenza compared with older children, this risk is much lower than the risk for children younger than 2 years old. Providers should use clinical judgment to guide treatment decisions for healthy children.

VACCINATIONS:
Why should someone receive the flu vaccine?
A flu vaccine is the single best way to protect against influenza illness.

What are the differences in vaccines for H1N1?
There are two kinds of 2009 H1N1 vaccines being produced: a 2009 H1N1 "flu shot" that is given with a needle, usually in the arm; and the 2009 H1N1 nasal spray flu vaccine given via a nasal sprayer. The same manufacturers who produce seasonal flu vaccines are producing 2009 H1N1 vaccines for use in the United States and the vaccines are being made in the same way that the seasonal vaccines are made.

H1N1 "flu shot" — an inactivated vaccine (containing killed virus) that is given with a needle, usually in the arm. The indications for who can get the 2009 H1N1 flu shot are the same as for seasonal flu shots. The flu shot is approved for use in people 6 months of age and older, including healthy people, people with chronic medical conditions and pregnant women. The same manufacturers who produce seasonal flu shots are producing 2009 H1N1 flu shots for use in the United States this season. The 2009 H1N1 flu shot is being made in the same way that the seasonal flu shot is made.

H1N1 nasal spray flu vaccine — a vaccine made with live, weakened viruses that do not cause the flu (sometimes called LAIV for "live attenuated influenza vaccine"). The indications for who can get the 2009 H1N1 nasal spray vaccine are the same as for seasonal nasal spray vaccine. LAIV is approved for use in healthy* people 2 years to 49 years of age who are not pregnant. The nasal spray vaccine for use in the United States is being made by MedImmune, the same company that makes the seasonal nasal spray vaccine called “FluMist®.” The 2009 H1N1 nasal spray vaccine is being made in the same way as the seasonal nasal spray vaccine.

When should someone get vaccinated?
Vaccination against 2009 H1N1 should begin as soon as vaccine is available and continue throughout the influenza season, into December, January, and beyond. This is because the timing and duration of flu activity can vary. Flu seasons can last as late as April or May. By early October 2009, extensive 2009 H1N1 flu activity was being reported in the United States. It’s possible that there may be waves of 2009 H1N1 activity during the 2009-2010 flu season that hit communities more than once over the course of the season. While 2009 H1N1 viruses are likely to be the most common cause of influenza this season, CDC still expects that seasonal influenza viruses will circulate and continues to recommend that people get a seasonal flu vaccine to protect against seasonal flu viruses.

Who should get vaccinated?
CDC’s Advisory Committee on Immunization Practices (ACIP), a panel made up of medical and public health experts, met July 29, 2009, to make recommendations on who should receive the 2009 H1N1 vaccine when it becomes available. While the federal government has purchased enough vaccine so that anyone who wants to get vaccinated can, there are recommendations regarding who should receive vaccination first. These recommendations focus on people in five target groups who are at higher risk for 2009 H1N1 influenza or related complications, are likely to come in contact with influenza viruses as part of their occupation and could transmit influenza viruses to others in medical care settings, or are close contacts of infants younger than 6 months (who are too young to be vaccinated).
Initial target groups for vaccination are:
When vaccine is first available, ACIP recommends that programs and providers administer vaccine to people in the following five target groups (order of target groups does not indicate priority):
•    pregnant women,
•    people who live with or provide care for infants younger than 6 months (e.g., parents, siblings, and day care providers),
•    health care and emergency medical services personnel,
•    people 6 months through 24 years of age, and,
•    people 25 years through 64 years of age who have certain medical conditions that put them at higher risk for influenza-related complications.

Who should NOT be vaccinated?
There are some people who should not get any flu vaccine without first consulting a physician. These include:
•    People who have a severe allergy to chicken eggs.
•    People who have had a severe reaction to an influenza vaccination.
•    People who developed Guillain-Barré syndrome (GBS) within 6 weeks of getting an influenza vaccine previously. (For information, see General Questions and Answers on Guillain-Barré syndrome (GBS).
•    Children younger than 6 months of age (influenza vaccine is not approved for this age group), and
•    People who have a moderate-to-severe illness with a fever (they should wait until they recover to get vaccinated.)

What are vaccine side effects?
The same side effects typically associated with the seasonal flu shot and the seasonal nasal spray vaccine are expected with the 2009 H1N1 flu shot and 2009 H1N1 nasal spray vaccine. These are:
The flu shot: The viruses in the flu shot are killed (inactivated), so you cannot get the flu from a flu shot. Some minor side effects that could occur are:
•    Soreness, redness, or swelling where the shot was given
•    Fever (low grade)
•    Aches
If these problems occur, they begin soon after the shot, are usually mild, and usually last 1 to 2 days. Almost all people who receive influenza vaccine have no serious problems from it. However, on rare occasions, flu vaccination can cause serious problems, such as severe allergic reactions.
The nasal spray: The viruses in the nasal-spray vaccine are weakened and do not cause severe symptoms often associated with influenza illness. (In clinical studies, transmission of vaccine viruses to close contacts has occurred only rarely.)
In children, side effects from LAIV can include:
•    runny nose
•    wheezing
•    headache
•    vomiting
•    muscle aches
•    fever
In adults, side effects from LAIV can include
•    runny nose
•    headache
•    sore throat
•    cough

Sources: CDC, and Epilepsy.com